fixed possible NPE

cas-server-support-openid/src/main/java/org/jasig/cas/support/openid/authentication/principal/OpenIdServiceFactory.java

@@ -86,6 +86,9 @@ public class OpenIdServiceFactory extends AbstractServiceFactory<OpenIdService>
 
     @Override
     public OpenIdService createService(final String id) {
-        return new OpenIdService(id, id, null, this.openIdPrefixUrl, null);
+        final ParameterList paramList = new ParameterList();
+        final OpenIdServiceResponseBuilder builder = new OpenIdServiceResponseBuilder(serverManager,
+            centralAuthenticationService, paramList, this.openIdPrefixUrl);
+        return new OpenIdService(id, id, null, this.openIdPrefixUrl, builder);
     }
 }